Variable retraction valve



May 21, 1957 N ET GRIESHABER x-:rAL 2,792,846

` VARIABLE aETRAcTIoN VALVE original Filed Jan. 18. 195o j 2 snee'tssneet 1 May 21,1957 E: GRIESHABER Erm. 2,792,846

l vVARIABLE RETRAcTroN VALVE f Original iled Jan. 18. 1,95:l 2 sheets-sneer 2 jrzyenzons @y farler di @drier United States Patent() VARIABLE RETRACTION VALVE Emil Grieshaber and Kurt Froehlich, Milwaukee, Wis.,

assgnors to Nordberg Manufacturing Company, Milj Waukee, Wis., a corporation of Wisconsin Original application Ianuary 18, 1950, Serial No. 139,202,

now Patent No. 2,706,490, dated April 19, 1955. Divided and this application November 17, 1953, Serial No. 392,609

7 Claims. (Cl. 137-543.23)

This is a division of application Serial No. 139,202, iiled January 18, 1950, now patent No. 2,706,490 of April 19, 1955.

Our invention relates to fuel injection control means for internal combustion engines and, in particular, to de livery valves therefor, and has for one object an improved retraction valve assembly for controlling the ow of fuel to internal combustion engines.

Another object of our invention is a unitary retraction valve assembly, in which a single movable valve member provides wide variation in the quantity of fuel delivered.

Another object of our invention is a retraction valve usable with diesel engines and adapted efliciently to con trolthe delivery of liquid fuel in small and large quantities.

Another object of our invention is .a simple unitary retraction valve utilizable in a fuel pump to control the flow ofliquid fuelto a dual fuel engine adapted to operate on liquid fuel, gas fuel, or a combination of the two.

Another object of our invention is a simple unitary retractionvalve witha displacer piston located below the valve seat, which relieves the'pressure inthe fuel line after the fuel is injected.

Anotherobject of our invention is a retraction valve of the above-described type with a bypass or limited relief around the i displacer piston whereby, when a small amountA of fuel is injected by the pump, the valve lifts only a small amount which is provided for -by the displacer piston.

Another object of` our invention is a retraction valve assembly of the above-.described type with Ya displacer piston on it having separated relief portions or flats on the displacer piston.` f

Another object of our invention is a retraction valve with a displacer piston on it having a limited bypass or relief past the displacer piston with one surface of the displacerpiston being inclined so that the clearance progressively varies as the valve body lifts from the valve seat.

Other objects will appear from time to time in the course of the specication and claims.

We illustrate the invention more or less diagrammatically in the acompanying drawings wherein:

Figure 1 is an axial section through a valve and pump assemblyillustrating its application to a fuel injector;

Figure 2 is an axial section through the retraction valve assembly: on anw enlargedY scale;

Figure 3 is a section along the lines33 of Figure 2;

Figure 4 is a section similar to Figure 3 through a variant form of the invention;

Figure 5 is a section similar to` Figure 3 though a variant form of the invention; and

Figure` 6' is a side elevation of another modified form of our retraction valve structure;

Like parts are indicated by like symbols throughout the specification anddrawings'.

Referring to thev drawings, and for example to Figure 1, A generally indicates a fuel pump assembly, the deice tails of which do not of lthemselves form part of the pres* ent invention, and B indicates a, fuel injector assembly, the details of which` likewise do not in and of themselves form part of the present invention.

Suitably secured to the pump assembly A, and extending into one end thereof, we illustrate an outer sleeve 10 apertured to accommodate an inner sleeve 12 and a valve seat element 14, the sleeves 10 and 12 and the element 14 constituting a housing or the like. The valve seat element 14 has an outwardly extending flange 16 abutting an inner shoulder 18 of the member 10. It is confined in the position in which it is shown in Figure 1 by an abutting end 20 of the sleeve 12. A valvechamber 22 is shown as formed within the sleeve 12. A nut 24 is threaded into the interior of the sleeve 10 and has an end 26 abutting an outer ledge 28 of the member 12. Thus, when the nut 24 is tightened, the sleeve 12 is thrust against the flange 16 `of the valve seat element 14, and the valve seat element is irrnly thrust against the inner shoulder 18 of the sleeve 10. Any suitable packing rings or members 30 and 32 can beused, whereby leakage around the valve seat element 14 is prevented.

The sleeve 10`and its associated parts is shown in screwthreaded relation with a` surrounding housing member of the pump assembly A. Any suitable pressure ring 34 contines a suitable gasket or packing 36. The valve chamber has a bore 38 in the valve seat element 14 which is aligned with. and in communication with a pump cham ber 40. The valve chamber 22 is in communication with a fuel delivering passage 42 adapted to deliver fuel to a suitable line 44 extending4 to the injection valve assembly, B.

A retraction valve body is indicated generally at 46. in the form of Figure 2, the body 46 has a valve head 4S with a conic face or valve surface 50 opposed to a conic valve seat 52 formed about the bore 38 of the valve seat element 14. The valve stem 54 is shown as generally cruciform in cross-section with guide vanes 56 having surfaces which engage the inner surface of the cylindrical wall of the bore 38 and thus guide the valve body member 46; The valve body is normally biased toward its closed position by a conventional coil spring 57 which is con fined inthe chamber between the valve` body and the top of the chamber. Between the valve surface 50 and the valve stem 54 is a displacer piston portion 518. As will be clear from Figures 2 and 3, the displacer piston 5S has a generallyv cylindrical outer surface slightly inwardly spaced from the opposed surface ofthe cylindrical bore 38 ofthe valve seat element 14. Thus, after the valve body has been lifted, and while the displacer piston is within the cylindrical bore of the element 14, the gap or space between` it and the bore provides a bypass or relief around the displacer piston. ln the form of Figure 2, the upper ends off the vanes 56 are curved as at 60.

It will beunderstood that we can vary the structure of the retraction valve body to provide a leakage or bypassing. Thus in Figure 4, in connection with a cruciform valve stem, we form the displacer piston 62. with diametrically opposed flattened portions 64. The number. and shape ofthe attened portions eau be varied or controlled to provide the desired flow.

Similarly, in Figure 5, instead of employing attened. portions,` wemay provide clearance indentations or` notches 660i a different'shape, for example in the formlower surface inclined at '7.4,` to provide a progressively varying clearance as thevalve body lifts from the valve.

In all forms of our device there is thus a provision for a bypass around the displacer piston, the effect being that with small amounts of fuel, the valve will not lift the full amount which is provided by the displacer piston. It will be understood that at full lift, the valve operates like any other valve with displacer piston. The valve chamber is shown of somewhat different contour in Figures l and 2, it being a matter of choice as to the length of the spring and the contour of the valve chamber employed.

The use, operation, and function of our invention are as follows:

Our invention is applicable to the delivery of liquid diesel fuel in combustion ignition engines operating onv liquid fuel and also in engines operating on gaseous fuel with a liquid pilot oil for igniting the gaseous fuel, these being commonly termed dual fuel engines. While the engine is operating on gaseous fuel, the amount of fuel oil used for igniting the gas is so small that the ordinary delivery valve with constant retraction will not operate satisfactorily. A certain amount of retractive movement of the retraction valve causes a corresponding pressure drop in the line to the fuel injector. For pilot oil operation, the pressure in the fuel line is barely above the pressure set by the spring in the fuel injector, whereas for full load diesel operation the pressure in the fuel line is usually more than twice the pressure set by the spring in the injector. Thus, it` should be possible to operate without retraction for pilot operation and have an appropriate amount of retraction for diesel operation. We obtain this result by employing a bypass around the displacer piston as shown and described above.

During gaseous fuel operation, only a pilot quantity of diesel fuel is injected to ignite the gas. The effective stroke of the pump plunger is very short and the retraction valve body is raised only a slight amount and for a very short time. The valve surface 50 is only lifted a short distance away from the valve seat 52 in Figure 2, and the displacer piston does not rise above the valve seat 52. The pilot fuel ows through the limited relief formed between the displacer piston and the bore of the chamber during this short period before the coil spring 57 forces the valve surface back into engagement with the seat.

During diesel fuel operation, the effective stroke of the pump plunger is longer. At full load, it is quite long and a large quantity of diesel fuel flows by the retraction valve. At no load and the light loads, a smaller quantity of fuel is pumped and the effective stroke of the pump plunger is short, nevertheless the stroke is longer and the quantity of fuel pumped is Igreater than during gas fuel operation. no load to full load, the retraction valve is raised far enough above its seat so that the displacer piston rises above the seat 52. Because the displacer piston is above the seat and in the large part of the fuel chamber, it does not dene a limited relief with the bore and it no longer has any effect on the quantity of fuel pumped.

The viscosity of the fuel has a bearing on the type of limited relief used. We have shown three forms of limited reliefs, and a variation (Figure 6) that can be u sed with any one of the three. The particular type of limited relief chosen would be greatly governed by the intended use of the engine, itsoperating conditions, the type and quality of the diesel liquid fuel available, the temperatures and humidity of the geographical location, and so forth. All three have performed admirably under extreme climatic conditions.

It will be realized that whereas we have described and claimed a practical and operative device, nevertheless many changes may be made in the size, shape and disposition of parts without departing from the spirit and scope of our invention. We therefore wish our'description and drawings to be taken as in broad sense During diesel fuel operation, fromV illustrative or diagrammatic, rather than as limiting us to our precise showing herein.

We claim:

1. In a retraction delivery valve assembly adapted to be connecte-d between a fuel injection means and a fuel pump means, the assembly being constructed and arranged to control the fuel injection pressure to an internal com bustion dual fuel engine operating on diesel liquid fuel or gas fuel with pilot liquid fuel injection; the assembly including a housing member defining a fuel chamber of relatively uniform diameter with a bore portion of relatively uniform diameter forming an inlet at one end of the housing, said housing having an outlet bore at the other end, a valve seat formed in the housing member for the bore and the fuel chamber, a retraction delivery valve body movably disposed in the chamber with a valve surface opposed to the valve seat to control the flow of fuel through the housing member, the periphery of the valve body on the outlet side of the valve surface defining an area with the chamber which is greater than the area of the outlet bore, the retraction delivery valve body including a valve stem portion that projects into the bore of the chamber in all normal positions of lift of the retraction delivery valve body, yielding means biasing the valve surface on the retraction delivery valve body toward the valve seat in the chamber of the housing member to stop the ow of fuel through the chamber when insufiicient pressure to overcome the yielding means is applied to the inlet side of the retraction delivery valve body, and a displacer piston on the retraction delivery valve body spaced from said valve surface to provide two relatively distinct lift positions of the retraction delivery valve body beyond the valve closed position, namely a minimum lift position and a maximum lift position, and therefore to provide two relatively fixed amounts of retraction, the displacer piston being disposed in the bore when the valve surface on the retraction delivery Valve body is in engagement with the valve seat in the chamber of the housing member in the valve closed position, the displacer piston having a relatively sharp lower edge, the displacer piston having a longitudinal bypass defining a limited, relatively constant, external clearance with lthe bore when the piston is disposed therein, both during the initial minimum lift position and during the valve closed position.

2. The structure of claim 1 in which the displacer piston on the retraction delivery valve body -has a generally cylindrical exterior surface of constant diameter spaced inwardly from the inner surface of the bore at all points.

3. The structure of claim 1 in which the displacer piston on the retraction delivery valve body conforms generally to the inner surface of the bore and has a diameter generally equal to the diameter of the bore, but includes a plurality of disconnected bypass channels formed on its outer surface.

4. The structure of claim 3 in which the channels on` References Cited in the tile of this patent UNITED STATES PATENTS 1,370,322 Gartin Oct. 1, 1929 2,158,737 Wunsch May 16, 1939 2,163,313 Voit .lune 20, 1939 2,247,421 Tabb July 1, 1941 FOREIGN PATENTS 528,889 Germany July 4, 1931 

